Domperidone is a peripheral-specific antagonist of the dopamine receptor D2 (D2R), with antiemetic, gastrokinetic and galactagogue activities. Following administration, domperidone binds to D2R expressed by peripheral neurons; this inhibits dopamine binding and D2R-mediated signaling. Inhibition of peripheral D2R signaling prevents or relieves various gastrointestinal (GI) symptoms, such as nausea and vomiting, and may help relief reflux and symptoms of a variety of other upper GI disorders.